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MONITORING IN ANAESTHESIA

PRESENTED BY:STANLEY OGOCHUKWU OKERULU

ADMISSION NUMBER: 0911700097MODERATED BY:

DR ABDULLAHI (CONSULTANT ANAESTHESIOLOGIST)

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OUTLINE• DEFINITION OF TERMS• WHY MONITOR?• GOALS• MONITORING IN PAST AND PRESENT• PHYSIOLOGIC FUNCTION (COV-TND)• LOW AND HIGHT- TECH PATIENT MONITORING• CONCLUTION• REFERENCES

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DEFINATION OF TERMS• Monitoring: Monitor is from Monere means warning

• To monitor or monitoring generally means to be aware of the state of a system, to observe a situation for any changes which may occur over time, using a monitor or measuring/monitoring device of some sort.• In anaesthesia, monitoring aids to know when to make therapeutic

intervention and to guide the assessment of those interventions.

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CONT’D• AESTHESIA is the ability to feel or perceive sensations.• ANAESTHESIA: insensitivity to pain, especially as artificially induced by the

administration of gases or the injection of drugs before surgical operations. • In the practice of medicine, especially surgery, and dentistry, anesthesia (or

anaesthesia) is an induced, temporary state with one or more of the following characteristics: analgesia (relief from or prevention of pain), paralysis (extreme muscle relaxation), amnesia (loss of memory), and unconsciousness. • An anesthetic is an agent that causes anaesthesia. • A patient under the effects of anesthesia is anesthetized. • An anesthesiologist (US) or anaesthetist (UK) is a physician who performs

anesthesia.

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WHY MONITOR?• Disturbances can occur during surgery, they include but are not limited

to:

• Airway obstruction, Respiratory depression, Apnea.

• Cardiac depression, Arrhythmias, Bradycardia, Tachycardia.

• Hypertension, Hypotension, Hypervolaemia, Hypovolaemia, Fluid shifts.

• Hypothermia, Hyperthermia

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GOALSThe primary goal of Anaesthesia is to keep the patient safe in the

perioperative period.

Continuous monitoring of the patient during and after surgery allows early detection of problems and correction.

Even detection of equipment failure.

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Monitoring in the Past• Visual monitoring of

respiration and overall clinical appearance• Finger on pulse• Blood pressure

(sometimes) Finger on the pulse

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Harvey Cushing Not just a famous neurosurgeon … but the father of anesthesia monitoring

• Invented and popularized the anesthetic chart• Recorded both BP and HR• Emphasized the relationship between

vital signs and neurosurgical events ( increased intracranial pressure leads to hypertension and bradycardia )

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Concept Development

CRRTInfusion Devices

Physiological Monitoring

Ventilation

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MONITORING IN THE PRESENT• Standardized basic monitoring requirements

(guidelines) from the ASA (American Society of Anesthesiologists), CAS (Canadian Anesthesiologists’ Society) and other national societies

• Many integrated monitors available

• Many special purpose monitors available

• Many problems with existing monitors (e.g., cost, complexity, reliability, artifacts)

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Standards of Care

•Guidelines’ specify what is usually expected, while• ‘standards’ specify what is always expected.

• The current standards of Anaesthesia monitoring are published by the American Society of Anesthesiologists (ASA).• Failure to follow nationally published standards puts the provider at risk

for Licensing problems and lawsuits.

• The ASA standards were most recently updated in 2011.

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ASA Monitoring Guidelines• STANDARD I

Qualified anesthesia personnel shall be present in the room throughout the conduct of all general anesthetics, regional anesthetics and monitored anesthesia care.

i.eA person who is qualified to monitor, evaluate and care for the patient

must be present throughout the conduct of Anaesthesia

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ASA Monitoring Guidelines• STANDARD II

During all anesthetics, the patient’s oxygenation, ventilation, circulation and temperature shall be continually evaluated(monitored).

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Standard II• Oxygenation: Inspired oxygen. • Hemoglobin saturation with a pulse oximeter• and observation of skin color.

• Ventilation: Capnography. Tracheal intubation must be verified clinically and• by detection of exhaled CO2. • Mechanical ventilation must be monitored with an audible• disconnect monitor.

• Circulation: ECG monitoring, blood pressure measurement at least every• five minutes, and continuous monitoring of peripheral circulation• by palpation, auscultation, plethysmography, or arterial pressure.

• Temperature: Thermometry if temp. changes are anticipated, intended, or suspected

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“The only indispensable monitor is the presence, at all times, of a physician or an anesthesia assistant, under the immediate supervision of an anesthesiologist, with appropriate training and experience. Mechanical and electronic monitors are, at best, aids to vigilance. Such devices assist the anesthesiologist to ensure the integrity of the vital organs and, in particular, the adequacy of tissue perfusion and oxygenation.”

CAS Monitoring Guidelines

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• The following are required: • Pulse oximeter • Apparatus to measure blood pressure, either directly or

noninvasively • Electrocardiography • Capnography, when endotracheal tubes or laryngeal

masks are inserted. • Agent-specific anesthetic gas monitor, when inhalation

anesthetic agents are used.

CAS Monitoring Guidelines

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• The following shall be exclusively available for each patient: • Apparatus to measure temperature • Peripheral nerve stimulator, when neuromuscular

blocking drugs are used • Stethoscope — either precordial, esophageal or

paratracheal • Appropriate lighting to visualize an exposed portion of

the patient.

CAS Monitoring Guidelines

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• The following shall be immediately available:

• Spirometer for measurement of tidal volume.

CAS Monitoring Guidelines

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Physiologic Functions (COV-TND)• Circulation• Oxygenation• Ventilation• Temperature• Neuromuscular Transmission/Blockade• Depth of Anaesthesia

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Circulation• Clinical• Monitors

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Clinical• Capillary refill• Urine output : 0.5ml/kg – 1.5ml/kg/hr• Pulse volume• Skin temperature

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Monitors• NIBP – measured every 5 min in all cases• IBP• CVP• PA• PAOP(pulmonary artery occlusion pressure)• ECG• Cardiac output: thermodilution, dye dilution

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How to monitor oxygenation ?

•Blood colour•Blood gas analysis (PaO2)•Pulse oximetry (SaO2)•Oxy-hemoglobin saturation•Hemoximetry•Oxy-hemoglobin•Met-hemoglobin• Carboxy-hemoglobin

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Pulse Oximetry• Based on light absorption Characteristics of Hb• Oxygenated hemoglobin absorbs more infrared light and allows more

red light to pass through• Deoxygenated (or reduced) hemoglobin absorbs more red light and

allows more infrared light to pass through• Beer-lamberts law

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Light emitter with red and infrared LEDsOpposite the emitter is a photodetector

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Sources of error in Oximetry

• Ambient light• Low perfusion states• Motion artefacts• External dyes• Carboxyhaemoglobin• Saturation below 80%• Penumbra effect

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Ventilation• Visual assessment of respiratory rate and depth• Minute volume• Capnography- Mainstream- sidestream• Acid base/ PH

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Ventilation Monitors Anaesthesia machines have ventilator disconnect alarms and built-in flow meters (spirometers). These include high and low limit alarm settings. Continuous measurement of exhaled tidal volume can detect circuit leaks and hypoventilation.

Excessive airway pressure can result in patient injury, so Anaesthesia machines also include overpressure relief valves (APL valves), withoverpressure alarms.

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Temperature• Continuous monitoring is recommended but every 15 minutes is

acceptable• Core temperature monitoring Sites - Blood temp with thermistor of pulmonary artery catheter - Oesophageal - Tympanic membrane - Nasopharyngeal

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.• Peripheral monitoring sites- Axilla 0.5 °C less than core body temperature - Rectal - Skin( forehead) 1- 2 °C less than core body temperature

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Neuromuscular Block• To assess adequacy block to enable the start of surgery• To assess the adequacy of reversal

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.• Clinical assessment - Hand grip - Head lift >5s - Tongue protrusion• Peripheral nerve stimulator - Ulnar nerve - Facial nerve - Common peroneal nerve

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Common sites for electrodes

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Neuromuscular Blockade

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Neuromuscular Blockade

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Depth of Anaesthesia• Evans/PRST score• Isolated fore arm technique• End tidal inhalational monitoring• Lower oesophageal contractility• Evoked potentials• Bispectral Index (BIS)

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BIS Monitor

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BIS

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Multiparameter Monitor.

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Low Tech Patient Monitoring• Manual blood pressure cuff• Finger on the pulse and forehead• Monaural stethoscope

(heart and breath sounds)• Eye on the rebreathing bag (spontaneously breathing patient)• Watch respiratory pattern• Watch for undesired movements• Look at the patient’s face

• color OK? • diaphoresis present?• pupils

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Typical display. Perceptible output?

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High Tech Patient Monitoring

Examples of Multiparameter Patient Monitors

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High Tech Patient Monitoring

Some Specialized Patient Monitors

BIS Depth of Anesthesia Monitor

Evoked Potential Monitor

Transesophageal Echocardiography

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CONCLUTION• Patients under anesthesia must undergo continuous physiological

monitoring to ensure safety.

• YOUR PRESENCE IS PARAMOUNT IN ANAESTHESIA.

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REFERENCES• WIKIPEDIA• SLIDESHARE (PROF. AMIR B.CHANNA FFARCS)• LECTURES ( DR. ABDULLAHI)• http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3161462/

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THANKS FOR LISTENING